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This page describes products and general use; it is not medical advice.
A biohazard specimen bag, often sold as a “95 kPa bag”, is a sealable plastic bag that holds a closed specimen container so that any leak stays inside the bag. In US shipping rules it is the kind of product used as the secondary layer of a triple package. Laboratory staff, clinic staff and buyers who handle specimen transport use it, and this page explains what the 95 kPa figure means and which rules apply to the bag, and where the bag stops being enough on its own.
What a 95 kPa biohazard specimen bag is
It is a leak-resistant transport pouch, usually printed with the biohazard symbol, that holds one or more closed specimen tubes or cups. One manufacturer, Therapak (Avantor Clinical Services), describes its 95 kPa transport pouches and bags as suited to use as a secondary leakproof packaging for biological substances shipped under US Department of Transportation (DOT) and International Air Transport Association (IATA) rules, with a leak-resistant adhesive seal (manufacturer catalog).
It is a different product from the red or orange biohazard waste bag. For waste bags see biohazard bag and container requirements.
What 95 kPa means
The figure comes from the US hazardous materials regulations. For liquid Category B infectious substances shipped by aircraft, 49 CFR 173.199(b)(4) says the primary receptacle or the secondary packaging must withstand an internal pressure producing a pressure differential of not less than 95 kPa (0.95 bar, 14 psi) without leakage (eCFR). A bag marketed as “95 kPa” is one its maker states has been tested to that differential.
The regulation sets a performance requirement and does not name which package forms qualify, so a biohazard symbol on a bag does not by itself tell you it meets 95 kPa; the manufacturer’s stated rating does.
Where the bag sits in triple packaging
49 CFR 173.199(a)(1) requires a Category B infectious substance to be packaged in a triple packaging: a primary receptacle, a secondary packaging, and a rigid outer packaging (eCFR).
| Layer | What 49 CFR 173.199 requires | Role of the specimen bag |
|---|---|---|
| Primary receptacle (tube, cup, vial) | Leakproof for liquids; siftproof for solids | Goes inside the bag |
| Secondary packaging | Leakproof for liquids; siftproof for solids; absorbent material between primary and secondary, in an amount sufficient to absorb all the contents, for liquids | This is the layer a 95 kPa bag is sold to fill |
| Rigid outer packaging | Required; marked with a diamond-shaped mark at least 50 mm per side and the proper shipping name “Biological substances, Category B” | Not provided by the bag |
So a specimen bag alone is not a complete shipment: the rigid outer packaging and the marking are separate requirements. For Category A material (UN2814) see Packing Instruction 620 for Category A infectious substances; it is outside the scope of this page.
Specimen bag, waste bag and pneumatic-tube bag
| Product | Typical purpose | Where to read more |
|---|---|---|
| 95 kPa specimen transport bag | Secondary leakproof layer around closed specimen containers | This page |
| Biohazard waste bag (red bag) | Holding regulated medical waste for disposal | Biohazard bag and container requirements |
| Zip-lock bag for pneumatic tube systems | In-hospital transport of specimens by tube system | Specimen containers |
Types and sizes
The Therapak 95 kPa catalog lists these formats. Treat the figures as one manufacturer’s range, not a standard.
| Type | Size | Layout and features (per catalog) |
|---|---|---|
| Two-pocket bag | 7 x 11 in, 100 per pack | Front pocket for specimen tubes, back pocket for the requisition form; peel the white adhesive liner and fold the adhesive over the opening to seal the front pocket |
| Single-pocket bags | 12 x 15 in and 13 x 18 in, 250 per case | Larger single pocket |
| ShuttlePouch | 59 x 190 mm and 90 x 190 mm | Preinserted absorbent sheet; catalog lists it for IATA Packing Instruction 650 |
Some versions come with an absorbent pad and some do not; the catalog notes that absorbent is not inserted in the 7 x 11 in bag. As a second data point, a supplier listing for one 7 x 10.9 in bag (The Compliance Center, product PK-BIOBAG) states 95 kPa hydrostatic testing, a peel-and-press adhesive seal that needs no heat sealer, and an absorbent rated for about 825 ml of urine or 495 ml of blood.
How to choose
These criteria come from the regulations cited on this page.
- Pressure rating. For liquid specimens by air, the packaging must withstand a 95 kPa differential (49 CFR 173.199). Look for the manufacturer’s stated 95 kPa rating.
- Absorbent. For liquids, enough absorbent material between primary and secondary packaging to absorb all the contents (49 CFR 173.199). Check whether the bag includes it or whether you must add it, and its stated capacity.
- Puncture risk. If a specimen could puncture its primary container, OSHA requires the secondary container to be puncture-resistant (29 CFR 1910.1030(d)(2)(xiii)(C)).
- Labeling. A container that leaves the facility must be labeled or color-coded as OSHA describes (see below).
Labeling and closing under OSHA rules
For specimens of blood or other potentially infectious materials, OSHA’s bloodborne pathogens standard (29 CFR 1910.1030) says:
- Specimens must be placed in a container that prevents leakage during collection, handling, processing, storage, transport and shipping.
- The container must be closed before it is stored, transported or shipped, and labeled or color-coded as the standard describes. A facility that uses universal precautions need not label containers while they stay in the facility; labels are required once they leave.
- If the outside of the primary container is contaminated, place it in a second leakproof container that is also labeled or color-coded.
- Labels are fluorescent orange or orange-red (or predominantly so) with contrasting lettering or symbols and the biohazard legend, placed as close as feasible to the container and secured so they are not easily lost. See also laboratory safety symbols.
Safe use and handling basics
- Close the primary container before it goes into the bag, and seal the bag as its instructions direct.
- Keep the requisition form outside the specimen pocket where the bag provides a separate pocket for it.
- Follow the bag maker’s instructions for use and your facility’s exposure control plan. For transport between sites see medical courier services.
Common mistakes
- Treating any bag with a biohazard symbol as a 95 kPa transport bag; the symbol is a label, the rating is a test claim.
- Treating the bag as the whole package; triple packaging also needs a rigid outer packaging and the required marking.
- Using a waste bag to transport specimens, or a specimen bag for waste.
- Assuming absorbent is included without checking the product listing.
FAQ
What does 95 kPa mean on a specimen bag?
It refers to the pressure differential of not less than 95 kPa (about 14 psi) that 49 CFR 173.199 requires liquid Category B packaging to withstand without leaking on aircraft. The rating is the manufacturer’s statement that the bag was tested to it.
Is a specimen bag enough to ship a specimen?
No. 49 CFR 173.199 requires a primary receptacle, a secondary packaging and a rigid outer packaging, and the outer packaging carries the required mark and proper shipping name.
Does a specimen bag need absorbent material?
For liquid specimens, 49 CFR 173.199 requires absorbent material between the primary and secondary packaging in an amount sufficient to absorb all the contents. Some bags include it; check the product listing.
Is a 95 kPa bag the same as a biohazard waste bag?
No. A waste bag holds regulated medical waste for disposal; a 95 kPa bag is a transport pouch for specimens.
Sources
- 49 CFR 173.199, Category B infectious substances, eCFR, checked 2026-10-30: ecfr.gov
- 29 CFR 1910.1030, Bloodborne pathogens, OSHA, checked 2026-10-30: osha.gov
- Therapak (Avantor Clinical Services), 95 kPa bags catalog, checked 2026-10-30: therapak.resonantclinical.com
- The Compliance Center, PK-BIOBAG product page, checked 2026-10-30: thecompliancecenter.com
